MOLD | ? someone explain

Hi guys could someone explain this if possible the attic seems properly ventilated and there is no water damage roof is not leaking here is a picture could someone help me out determine what it could be any response is appreciated

MOLD | ? someone explain

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WELCOME to the forums, if I forgot to say it!

MOLD | ? someone explain

If any ads are present below my answer or words underlined/colored, I do not condone/support/use the product or services listed/linked to, they are there without my consent.
WELCOME to the forums, if I forgot to say it!